The object of the Code is very transparent on the fact that all prescriptive rules of the Code address the objective-based fundamental safety principles of the IEC Standard “Electrical Installations of Buildings”.
This standard, IEC 60364-I, comprises the following types of protection:
- against electric shock (direct and indirect contact);
- against thermal effect (high temperature or electric arc);
- against overcurrent (damage due to excessive temperatures or electromechanical stress caused by overcurrents likely to arise on live conductors);
- against fault currents (against dynamic and thermal effects of fault currents); and
- against over-voltage (harmful effects due of a fault between live parts of circuits supplied at different voltages).
Thus, it is quite obvious that the prescriptive requirements of the CE Code represent very focused acceptable means by which objective-based fundamental safety principles of IEC 60364-I may be accomplished. Rules of the installations are well coordinated and correlated between different sections of the Code. Rules of General Sections are applicable throughout the Code, unless they are specifically modified or amended by particular rules of Supplementary or Amendatory Sections. Sections 0 to 16 and Section 26 are considered to be “General Sections”, and other sections are “Supplementary or Amendatory”.
For example, Rule 6-206 (in General Section 6) mandates that a service box must be installed within the building being served, and that the deviation from this requirement may be entertained only under provisions of a special permission.
However, Section 36 (which is amendatory to General Sections) allows outdoor installation of the H.V. service boxes. Another example is Rule 14-104. Although, in general, this rule states that the rating or setting of overcurrent devices must not exceed the allowable ampacity of conductors that these o/c devices protect, the Rule further allows deviations from this requirement if the conditions of Table 13 are met, or if particular provisions for coordination between the allowable ampacity of conductors and the o/c devices protecting these conductors are governed by other rules of the Code.
In fact, these latter criteria could apply for General and Supplementary Sections. For instance, perfect examples of deviations from Rule 14-104 permitted by the Code are: Rules 26-208 and 26-210. These rules belong to another General Section (Section 26). But they govern installation of capacitors (of a very specific equipment that requires a unique coordination between the setting of the overcurrent devices and ampacity of conductors protected by these o/c devices), and as such these particular rules of Section 26 represent an exception to general provisions of Rule 14-104.
Other similar examples may be found in various supplementary sections (i.e., Rules 28-106 and 28-200 — for motors; Rule 62-114(7) and (8) — for space heating, etc.).
It is interesting to note that requirements of the installation Code (CEC, Part ) are also coordinated with provisions of the safety standards for electrical products (for electrical equipment, cables and wiring devices). In fact, each of these product standards states in its scope that the standard covers design and construction requirements of a specific type of electrical product that is intended to be installed in conformance with the CE Code, Part I.
No wonder that the installation Code is called the CEC, Part I, and each safety standard for an electrical product is called CSA Part II Standard.
So, this coordination perfectly demonstrates the fact that the safety requirements for design and construction of electrical products and installation rules represent two separate but complimentary parts of the single Canadian Electrical Code.
As it was mentioned above, the rules of the Code are correlated through the document to create a set of versatile and comprehensive requirements for safe electrical installations.
However, there are numerous relaxations from these rules in the body of the Code. These relaxations are manifested by notwithstanding clauses or statements such as “it shall be permitted”. These relaxing provisions are clearly linked to the specific conditions of installations, spelled in the rule. But there are also circumstances, where Code allows deviations from its prescriptive requirements based not on specific technical conditions, but rather on the fact that each such deviation may be obtained for the particular installation only from the authority that provides a regulatory enforcement of the installation.
Each situation where a deviation from the rules is deemed to be possible is conditional to provisions of Rule 2-030 “deviation of postponement”. Under this Rule, a designer (or an electrical contractor who obtained a permit for the electrical work) may approach the regulator with a request to deviate from a specific prescriptive requirement of the Code. Each such request must relate to a very particular installation (i.e., it must be unique, and not be used as a blanket approach), and it must be clearly substantiated that the relevant objective-based fundamental safety principles of the IEC 60364 (see above listed types of protection described by the IEC 60364) are fully met by that unique request.
Regulators evaluate each such request and may grant a special permission to deviate from the Code requirements for the particular installation.
However, the regulatory authority cannot grant a special permission for use of unapproved equipment. All equipment (except for provisions of Rule 16-222(2)) must be approved in order to be installed under rules of the CE Code, Part I. Code users should note that approved is the defined term, and this definition is clearly spelled out in the Code.
It should be also noted that the local regulatory authority must be consulted on a matter of deviations in every particular case of installation.
